Electromagnetic switch



Dec. 2, 1941. w.'B. ELLWOOD V 2,264,743v ELECTROMAGNETIC SWITCH FiledJunev 27, 1940 FIG.

I INVENTOR v mafluvooo 1 I 'U I,

4 TTORNE V Patented Dec. 2, 1941 ELECTROMAGNETIC SWITCH Walter B.Ellwood, New York, N. Y., assignor to Bell Telephone Laboratories,

Incorporated,

New York, N. Y., a corporation of New York Application June 2'1, 1940,Serial No. 342,629

2 Claims.

This invention relates to switches and particularly toelectromagneticaliy operated switches.

The object of the invention is to provide a relay unit contact devicewhich is economical, reliable and easily replaceable.

A feature of the invention is a contact arrangement for transferoperation consisting essentially of contacts of magnetic material sealedin a vessel either. evacuated or filled with an inert gas which may beoperated by an external magnetic force whereby costly contact metals areeliminated. To secure transfer operations two magnetic elements areplaced lengthwise in the vessel and are slightly overlapping butnormally out of contact with each other. To one of these elements issecured by insulation a third and nonmagnetic member which is normallyin contact with the other said magnetic element. When an externalmagnetic force is applied to this unit the two magnetic members whichform part of the magnetic circuit as well as part of the electricalcircuit of the device are moved together whereby the contact from thesecond magnetic element is transferred from the non-magnetic element tothe first magnetic element since the external magnetic force acts todiminish the air-gap between the two said magnetic elements. Theconstruction of this device involves the use of an insulating member tomaintain constant separation between the said non-magnetic element andits associated magnetic element, whereby the second magnetic elementthus effectively travels between the two.

Another feature of the invention is the use of a movable contactassembly. In this type relay where the part corresponding to thearmature'in a normal relay and the part corresponding to the frontcontact in a normal relay are both part of the magnetic circuit and bothare subject to movement when energized, the part corresponding to theback contact of a normal relay must be made comparatively flexible andcaused to move with the front contact since the direction of movement ofsuch front contact is toward the back contact. r

This contact device is of the general nature shown in Patent 2,187,115to Ellwood et al., January 16, 1940. v

The drawing consists of a single sheet showing three cross-section viewsof the contact unit.

Fig. 1 shows a cross-section of the unit when taken lengthwise. l is aglass envelope which may be evacuated or filled with an inert gas toprevent corrosion or oxidation. 2 is a terminal entering the envelope towhich is attached a resilient magnetic member 3. At the other end ofthis device a non-magnetic member 4 and a conducting member 5 are sealedinto the glass. A magnetic member 6 is attached to the conducting member5 in any well-known manner, for instance, by welding. The non-magneticmember 4 and the magnetic member 6 are held to a permanent degree ofseparation by an insulating piece 1. The non-magnetic member 4, themagnetic member 6 and the insulating piece I may be slightly movable asa unit.

As shown in Fig. 1 the contact device is nonoperated and a connection ismade between the non-magnetic member 4 and the magnetic member 3. InFig. 2 the device is shown in its operated position with contact beingmade between the magnetic member 6 and the magnetic member 3. Thisillustrates. how the insulating piece I prevents the non-magnetic member4 which is tensioned'downwardly from following the nonmagnetic member 3when it moves into contact with the magnetic member 5. Fig. 3 shows across-section on the lines 3 3 to illustrate one method by which theinsulating piece I may be attached to the non-magnetic member 4 and themagnetic member 6.

This contact device may be operated by a coil external to the envelope Iwhereby the magnetic members 3 and 6 become part of the magnetic circuitas well as part of the electrical circuit of the device.

What is claimed is:

v 1. A magnetically operated switch structure comprising a pair ofmagnetic reeds mounted longitudinally in an evacuated or inertgas-filled tube with their inner ends overlapping but normally out ofcontact with each other, a third non-magnetic element mountedlongitudinally and permanently spaced from its companion magnetic reedby insulation whereby said nonmagnetic member and its companion magneticreed will flex as a unit, said non-magnetic member being normally incontact with the other of said magnetic reeds, and means for producing amagnetomotive force along the axis of said tube for causing the normalair gap between said magnetic reeds to shorten to cause a transfer ofcontacts between said elements.

2. A magnetically operated switch structure comprising an evacuated orinert gas-filled tube, a magnetic reed sealed into one end of said tubeand extending parallel to the axis of said tube, another magnetic reedsealed into the other end of said tube and extending parallel to theaxis of said tube, the other ends of said magnetic toward each other thecontact between said set! 0nd reed and said non-maanetic member will bebroken and a contact between said magnetic reeds will be established.and means for energizin: said contact device by a field extending alongthe axis of said tube.

WALTER B. ELI-WOOD.

